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排序方式: 共有125条查询结果,搜索用时 15 毫秒
1.
The human cholesteryl ester (CE) and triglyceride (TG) exchange protein (denoted LTC or lipid transfer complex) was isolated in a single step from plasma using immunoaffinity batch extraction. Antibodies were raised against two preparations of conventionally purified LTC. LTC-I and LTC-II (purified 20,000-fold and 3500-fold, respectively) were used as immunogens. The antiLTC antibodies were isolated by anion-exchange chromatography and coupled to Affi-Gel 10. Chromatography of plasma on antiLTC Affi-Gel removed all of the CE and TG transfer activity. Moreover, LTC prepared from both antiLTC-I and antiLTC-II-Affi-Gel matrices were identical when analyzed by sodium dodecyl sulfate-polyacrylamide gel LTC electrophoresis. LTC exhibited two protein bands of Mr (apparent) 67,000 and 58,000 and a broad, faintly staining region at greater than 150,000. Analysis of LTC by immunoblotting indicated that both antiLTC-I and antiLTC-II antibodies recognized the same LTC proteins. Isoelectric focussing of LTC gave two pI values, 5.2 and 8.7. These data suggest that LTC is a complex of specific proteins and perhaps lipid. Specific CE and TG exchange activities of immunoaffinity-purified LTC were comparable, although the activities were low with respect to that of the antigen used to generate antiLTC-I. This is not due to contamination of LTC by albumin, lecithin:cholesterol acyltransferase, or apolipoproteins AI, AII, B, CIII, D, or E. 相似文献
2.
Free and polymerized tubulin in cultured bone cells and Chinese hamster ovary cells: the influence of cold and hormones 总被引:1,自引:1,他引:0
A low pH method of liposome-membrane fusion (Schneider et al., 1980, Proc. Natl. Acad. Sci. U. S. A. 77:442) was used to enrich the mitochondrial inner membrane lipid bilayer 30-700% with exogenous phospholipid and cholesterol. By varying the phospholipid-to- cholesterol ratio of the liposomes it was possible to incorporate specific amounts of cholesterol (up to 44 mol %) into the inner membrane bilayer in a controlled fashion. The membrane surface area increased proportionally to the increase in total membrane bilayer lipid. Inner membrane enriched with phospholipid only, or with phospholipid plus cholesterol up to 20 mol %, showed randomly distributed intramembrane particles (integral proteins) in the membrane plane, and the average distance between intramembrane particles increased proportionally to the amount of newly incorporated lipid. Membranes containing between 20 and 27 mol % cholesterol exhibited small clusters of intramembrane particles while cholesterol contents above 27 mol % resulted in larger aggregations of intramembrane particles. In phospholipid-enriched membranes with randomly dispersed intramembrane particles, electron transfer activities from NADH- and succinate-dehydrogenase to cytochrome c decreased proportionally to the increase in distance between the particles. In contrast, these electron- transfer activities increased with decreasing distances between intramembrane particles brought about by cholesterol incorporation. These results indicate that (a) catalytically interacting redox components in the mitochondrial inner membrane such as the dehydrogenase complexes, ubiquinone, and heme proteins are independent, laterally diffusible components; (b) the average distance between these redox components is effected by the available surface area of the membrane lipid bilayer; and (c) the distance over which redox components diffuse before collision and electron transfer mediates the rate of such transfer. 相似文献
3.
Peter Ihm 《Molecular & general genetics : MGG》1955,87(1):36-46
Zusammenfassung Für die Untersuchung der Ausbreitung von Organismen in der Ebenen werden statistische Methoden ausgearbeitet, die eine Untersuchung der systematischen Ortsveränderung und der Dispersion ermöglichen. Dabei wird einmal ein spezieller, einmal ein allgemeiner Fall einer zweidimensionalen Normalverteilung angenommen. Bei Konjunktionen von Aussagen über Parameter werden simultane Konfidenzbereiche angegeben. In einem Anhang werden aufgestellte Behauptungen bewiesen.Mit 4 Textabbildungen. 相似文献
4.
M. Rita I. Young Joe Ihm Yvonne Lozano Mark A. Wright M. Margaret Prechel 《Cancer immunology, immunotherapy : CII》1995,41(1):37-45
Metastatic Lewis lung carcinoma (LLC-LN7) tumors that secrete granulocyte/macrophage-colonystimulating factor (GM-CSF) stimulate myelopoiesis and induce bone marrow-derived immunosuppressor cells that are homologous to granulocyte/macrophage progenitor cells. In vitro treatment of the LLC-LN7 cells with 1,25-dihydroxyvitamin D3 reduced tumor cell production of suppressor-inducing activity, although suppressor-inducing activity could be restored by reconstituting the tumor supernatants with recombinant GM-CSF. Treatment of mice having LLC-LN7 tumors with vitamin D3 reduced tumor production of GM-CSF and the frequency of myeloid progenitor cells. This was associated with a reduction in immunosuppressor activity and an increase in T cell function. Vitamin D3 treatment of mice having palpable tumors transiently retarded tumor growth, but caused a prominent reduction in tumor metastasis. Treating mice with vitamin D3 after tumor excision resulted in a reduction in the tumor-induced myelopoietic stimulation and associated immunosuppressive activity, and enhanced T cell function. These mice had a markedly reduced incidence of tumor recurrence. The results of this study suggest that vitamin D3 treatment of mice with GM-CSF-secreting tumors can interrupt the myelopoiesis-associated immunosuppressor cascade and, in turn, reduce tumor metastasis and recurrence.This study was supported in part by grants from the Medical Research Service of the Department of Veterans Affairs and by grants CA-45080 and CA-48080 from the National Institutes of Health 相似文献
5.
Movements and associations of ribosomal subunits in a secretory cell during growth inhibition by starvation
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In Chironomus tentans salivary gland cells, the cytoplasm can be dissected into concentric zones situated at increasing distances from the nuclear envelope. After RNA labeling, the newly made ribosomal subunits are found in the cytoplasm mainly in the neighborhood of the nucleus with a gradient of increasing abundance towards the periphery of the cell. The gradient for the small subunit lasts for a few hours and disappears entirely after treatment with puromycin. The large subunit also forms a gradient but one which is only partially abolished by puromycin. The residual gradient which which is resistant to the addition of the drug is probably due to the binding of some large ribosomal units to the membranes of the endoplasmic reticulum (J.-E. Edstrom and u. Lonn. 1976. J. Cell Biol. 70:562-572, and U. Lonn and J.-E. Edstrom. 1976. J. Cell. Biol. 70:573-580). If growth is inhibited by starvation, only the puromycin-sensitive type gradient is observed for the large subunit, suggesting that the attachment of these newly made subunits to the endoplasmic reticulum membranes will not occur. If, on the other hand, the drug-resistant gradient is allowed to form in feeding animals, it is conserved during a subsequent starvation for longer periods than in control feeding animals. This observation provides a further support for an effect of starvation on the normal turnover of the large subunits associated with the endoplasmic reticulum. These results also indicate a considerable structural stability in the cytoplasm of these cells worth little or no gross redistribution of cytoplasmic structures over a period of at least 6 days. 相似文献
6.
Taner Z Sen Andrzej Kloczkowski Robert L Jernigan Changhui Yan Vasant Honavar Kai-Ming Ho Cai-Zhuang Wang Yungok Ihm Haibo Cao Xun Gu Drena Dobbs 《BMC bioinformatics》2004,5(1):1-11
Background
Protein-protein interactions play a critical role in protein function. Completion of many genomes is being followed rapidly by major efforts to identify interacting protein pairs experimentally in order to decipher the networks of interacting, coordinated-in-action proteins. Identification of protein-protein interaction sites and detection of specific amino acids that contribute to the specificity and the strength of protein interactions is an important problem with broad applications ranging from rational drug design to the analysis of metabolic and signal transduction networks.Results
In order to increase the power of predictive methods for protein-protein interaction sites, we have developed a consensus methodology for combining four different methods. These approaches include: data mining using Support Vector Machines, threading through protein structures, prediction of conserved residues on the protein surface by analysis of phylogenetic trees, and the Conservatism of Conservatism method of Mirny and Shakhnovich. Results obtained on a dataset of hydrolase-inhibitor complexes demonstrate that the combination of all four methods yield improved predictions over the individual methods.Conclusions
We developed a consensus method for predicting protein-protein interface residues by combining sequence and structure-based methods. The success of our consensus approach suggests that similar methodologies can be developed to improve prediction accuracies for other bioinformatic problems. 相似文献7.
Poly(4-vinylimidazole) (P4V) was obtained by free radical polymerization of 4-vinylimidazole (4V) prepared by decarboxylation of urocanic acid. P4V formed a complex with DNA that exhibited higher transfection effiency on Hela cells than polyethylenimine (PEI), through the proton sponge mechanism of the imidazole groups in the side chain of the P4V, and low cell toxicity. 相似文献
8.
Baart GJ Zomer B de Haan A van der Pol LA Beuvery EC Tramper J Martens DE 《Genome biology》2007,8(7):R136
Background
Neisseria meningitidis is a human pathogen that can infect diverse sites within the human host. The major diseases caused by N. meningitidis are responsible for death and disability, especially in young infants. In general, most of the recent work on N. meningitidis focuses on potential antigens and their functions, immunogenicity, and pathogenicity mechanisms. Very little work has been carried out on Neisseria primary metabolism over the past 25 years. 相似文献9.
Eoghan M Cunnane John JE Mulvihill Hilary E Barrett Michael T Walsh 《Biomedical engineering online》2015,14(Z1):S7
Background
Due to the limited number of experimental studies that mechanically characterise human atherosclerotic plaque tissue from the femoral arteries, a recent trend has emerged in current literature whereby one set of material data based on aortic plaque tissue is employed to numerically represent diseased femoral artery tissue. This study aims to generate novel vessel-appropriate material models for femoral plaque tissue and assess the influence of using material models based on experimental data generated from aortic plaque testing to represent diseased femoral arterial tissue.Methods
Novel material models based on experimental data generated from testing of atherosclerotic femoral artery tissue are developed and a computational analysis of the revascularisation of a quarter model idealised diseased femoral artery from a 90% diameter stenosis to a 10% diameter stenosis is performed using these novel material models. The simulation is also performed using material models based on experimental data obtained from aortic plaque testing in order to examine the effect of employing vessel appropriate material models versus those currently employed in literature to represent femoral plaque tissue.Results
Simulations that employ material models based on atherosclerotic aortic tissue exhibit much higher maximum principal stresses within the plaque than simulations that employ material models based on atherosclerotic femoral tissue. Specifically, employing a material model based on calcified aortic tissue, instead of one based on heavily calcified femoral tissue, to represent diseased femoral arterial vessels results in a 487 fold increase in maximum principal stress within the plaque at a depth of 0.8 mm from the lumen.Conclusions
Large differences are induced on numerical results as a consequence of employing material models based on aortic plaque, in place of material models based on femoral plaque, to represent a diseased femoral vessel. Due to these large discrepancies, future studies should seek to employ vessel-appropriate material models to simulate the response of diseased femoral tissue in order to obtain the most accurate numerical results.10.